Automatic firearm breech bolt locking mechanism



Sept. 26, 1950 H. LIPPERT E1- AL 2,523,704

AUTOMATIC FIREARM BREECH BOLT LOCKING MECHANISM Filed Nov. 5, 1946 2 Sheets-Sheet 1 'FigJ 3 2 2/22 Patented Sept. 26, 1950 AUTOMATIC FIREARM BREECH BOLT LOCKING MECHANISM Hanns Lippert and Erwin Hepperle, Zurich, Switzerland, assignors to Verwaltungsgesellschaft der Werkzengmaschinenfabrik Oerlikon, Zurich-Oerlikon, a Swiss company Application November 5, 1946, serial No. 707,968 In Switzerland November 7, 1945 17 Claims. l

Co-pending application Ser. No. 661,310 discloses an automatic fire-arm with one-piece breech including a pre-tensioned energy accumulator, and in which the locking organ is brought into locked position as soon as the breech has reached its end position.

The present invention now relates to a particularly simple constructional example of the principle disclosed in the above-mentioned copending application Ser. No. 661,310. The automatic lire-arm according to the present invention is characterised by the feature that the energy accumulator consists of two parts abutted by the springs serving to accumulate the energy the accumulator being tensioned by levers actuated by the breech block, and that furthermore the lock has a seating in the breech casing. As suitable means for tensioning the energy accumulator, double levers may be provided, seated close to the cartridge chamber and actuated by the breech block on its forward travel as soon as it is close to its forward end position. The action of the energy accumulator on the lock for initiating the locking movement can be intensified by the breech block dealing the energy accumulator a rebound blow. Lastly, the energy accumulator can be designed so that its rear part supports the lock in locked position. The unlocking movement can be started by a gas rod acting, over a double lever, on the rear part of the energy accumulator and removing the latter out of the lock-supporting position, or else levers can be provided, seated on the parts moving to and fro and connected with the rear part of the energy accumulator, which levers, in the course of the rearward travel of the barrel together with the breech casing, hit a stop fitted to the cradle, thus removing the energy accumulator out of the locksupporting position. The contacting surfaces of the lock with the breech block may be'suitably made of such shape that unlocking shall take place automatically on removing the support afforded to the lock by the rear part of the energy accumulator.

The attached drawing shows two constructional examples of the subject of the invention. In this drawing:

Fig. l is the schematic set-up of a re-arm according to a rst constructional example in section;

Fig. 2 shows the breech and the organs carrying out the locking operation, during the forward travel of the breech block;

Fig. 3 is a section along line I-I in Fig. 2;

Fig. 4 shows the breech block and the organs carrying out the-locking operation, as they are just before the breech block reaches its forward end position;

Fig. 5 shows the breechblock and the organs carrying out4 the locking operation, lin locked position; l Y

Fig.VV 6 shows the breech block and the organs carrying out the locking operation, on release of the shot, before unlocking;

Fig. 7 is the schematic set-up of a fire-ar according to a second constructional example, in section;

Fig. 8 shows the breech block and the organs carrying out the locking operation, during the forward travel of the breech block;

Fig. 9 shows the breech block and the organs carrying out the locking operation, in locked position;

Fig. 10 shows the breech block and the organs carrying out the locking operation, in the position they occupy upon release of the shot, be-V fore unlocking; and

Fig. 11 is a top View (part in section) along line lI-II in Fig. 10.

In Fig. 1, I designates the barrel inserted in the breech casing 2 by means of a bayonet joint 3. The one-piece breech block 4 slides in the breech casing 2 and stands under the action of the recuperating spring 5. 6 is a schematic representation of the trigger mechanism. In the breech casing is fitted the lock 'I in a seating 8 suitably made of hard metal and inserted in the breech casing,V the lock being supported on parts 9 and Ill of the energy accumulator. The energy accumulator consists of two parts 9 and lll (Fig. 3) of tubular shape in front seated in the breech casing 2, and two bodies II in which are tted springs I2 driving apart the parts 9` and I0 in relation to the bodies Il (Fig. 2). Into each of the bodies Il, on both sides of the breech block, there engages a double lever I3, by means of a spherical projection I3a, which double levers are seated in the breech casing 2 Y close to vthe cartridge chamber, by means of bolts I4 (see also Fig. 11 of the second constructional example). With the arm I5 the double levers I3 engage the path of noses 4a on breech block 4 and-as represented in Fig. 2 are swung by the breech block 4 on its forward travel. Parts 9 and IB of the energy accumulator areprovided with shoulders I6 (Fig. 4) into each of which engages a spherical projection Ila of .a lever I'I seated on the breech cas- 3 ing 2 by means of the bolt I8, and on the arm I9 of which the gas rod 2S acts (Fig. 5).

The bodies II on which the levers I3 act and in which are also inserted the springs I2, are fitted with two rods 2I and 22 seated in the breech casing (Fig. 3). These two rods extend with noses IIa beyond the lock 1 and serve to maintain it in position during the rearward and forward travel of the breech block, i. e. in unlocked position.

The lock on which, during the rearward and forward travel of the breech block, the pre-V tensioned springs I2 act, and which therefore has the tendency to escape upward, is thus prevented from rubbing (grating) against the breech block moving to and fro, which would tend to lower the firing rate.

The working of the fire-arm just described is briefly as follows: During the forward travel of the breech block the noses I Ia of the rods 2I and 22 force downward the lock 'I, so that it remains in the position shown in Fig. 2. As soon as the breech block il comes near its forwardmost position, it strikes with noses da the arm I of the double levers I3, swinging them, and thus causing the energy accumulator to take up the tensioned position, as shown in Fig. 4. The rods 2i, 22, in accordance with the movement carried out by the levers I3 and transmitted on to the bodies II, have meanwhile been pulled back, releasing the lock In this position, however, the bodies I I are in contact with the parts 9 and IIJ. There from follows that the further forward travel of the breech block, acting by way of the levers I3, causes the bodies I I and the parts 9 and i8 compulsorily to move together rearwardly. Since the lock-supporting face 4b of the breech block 4 has now allowed the lock to enter, the lock 'I is swung in under pressure through the movement imparted by the breech block to the levers I3 over bodies I I and parts 9 and I I), the movement being initiated by a rebound blow. The torque causing the lock l to rotate is brought about by the fact that the energy accumulator engages the lock I by means of Slanting faces 9a and 7a.. On the breech block Q reaching its forward reversal position, the lock I is cammed upward and catches behind the breech block 4. Parts 9 and II'I of the energy accumulator are now pushed underneath the lock F-the energy accumulator being at the same time unstressed-thus affording it support.

Upon release of the shot the lever I'I is swung round the bolt I8 by the gas rod 2U, and parts 9 and I0 of the energy accumulator pressed forward, tensioning the springs I2, thus depriving the lock 'I of its support by parts 9 and I0. Since the faces lb and (ib with which the lock I contacts the breech 4 are self-unlocking, the lock 1, under the action of the remaining gas pressure, is forced downward, as indicated by an arrow in Fig. 6, and consequently the breech block 4 unlocked, so thatunder the action of the remaining gas pressure forces-it can be driven back against the recuperating spring 5. The self-unlocking action is due to the fact that the direction of the force transmitted by the breech block to the lock 7 forms with the straight line connecting the center of the force-transmitting area of the engaging surfaces lib, 1b, and the fulcrum of the lock, an angle which is greater than the angle of friction, so that upon removal of the underlapping portions of the parts 9 and IB of the energy accumulator from under the lock, unlocking occurs automatically.

Under the action of the springs I 2, tensioned anew as described above, the levers I3 now take up the position shown in Fig. 2, the rods 2| and 22 catching with noses IIa over shoulders 1c on the lock 'I (Fig. 11) thus holding the lock in position.

In Figs. 7-11 is shown a further constructional example for the return of the parts 9 and IIJ of the energy accumulator, for the purpose of removing the support of the lock 1, al1 other parts, however, remaining the same. The breech casing 2 is fitted laterally with two fork-shaped levers 23, seated in the casing by means of bolts 24. The fork-shaped levers 23 are fixed to parts 9 and II) of the energy accumulator by means of pivots 25 (Fig. 11). The levers 23 are provided with cams 2B, whilst a stop 28 is fitted on the cradle 21.

Upon release of the shot, the barrel I and the breech casing 2 move backward, so that the cams 26 of the levers 23 strikeV the stop 28 of the cradle 2, thus keeping back the parts 9 and II) of the energy accumulator, and depriving the lock I of its support through parts 9 and I0. All other parts are the same as in the constructional eX ample according to Figs. l-6.

We claim:

l. Automatic fire-arm comprising a breech casing, a one-piece breechblock slidable therein, means mounted in the breech casing for locking the breechblock against movement relative tothe casing, mechanism for bringing the locking means into locking position and comprising a pre-tensionable energy accumulator having two parts and a spring acting on said parts and serving to accumulate the energy, and mechanism actuated by the breechblock for tensioning the energy accumulator.

2. Automatic fire-arm according to claim 1, wherein the breech casing is provided with a cartridge chamber and wherein the tensioning mechanism comprises a double lever mounted close to the cartridge chamber and actuated by the breechblock on its forward travel close toits front reversal position.

3. Automatic fire-arm according to claim 1, wherein the rear portion of the energy accumulator is arranged to catch underneath the locking means to hold it in locked position.

4. Automatic fire-arm according to claim 1, wherein the rear portion of the energy accumulator bears against the locking means in its inoperative position by way of inclined cam surfaces which act to move the locking means into locking position when said means are released.

5. Automatic fire-arm according to claim 1, including a lever actuated by the breech block on its forward movement and arranged to move one part of the energy accumulator rapidly toward the other and to engage the same with sudden impact with tensioning of the spring fitted between them, whereby the movement imparted by the breech block to said lever is transmitted on to the locking means with sharp impact pressure.

6. Automatic nre-arm according to claim l, including a, gas rod for initiating the unlocking motion, and a double lever acting on the rear part of the energy accumulator and operated by the gas rod to remove said rear part out of the position in which it holds the locking means in operative position.

7. Automatic fire-arm according to claim l, including a cradle for slidably supporting the breech casing, a stop on the cradle, and a lever pivoted on the breech casing and connected with the rear part of the energy accumulator, said lever being so disposed that during the rearward travel of the breech casing, it strikes said stop and is rotated so as to remove the energy accumulator out of the position in which it holds the locking means in operative position.

8. Automatic fire-arm according to claim 1, vvhereinI the front part of the energy accumulator is provided with a rod supported in the breech casing and acting to keep the locking means in the unlocking position.

9. Automatic fire-arm comprising a cradle; a breech casing slidable on the cradle; a breech block slidable in the casing; and means for locking and releasing the breech block and comprising a locking member seated in the breech casing and normally disposed out of the path of the breech block, and an energy accumulator including a front part, a rear part, and a compression spring disposed between said parts, the rear face of the rear part engaging the locking member along inclined surfaces of such shape that the locking member is urged into locking position, a rod connected with the front part and normally overlying the locking member to hold the same in inoperative position, means actuated by the breech block on its forward travel to shift the front part of the energy accumulator to cause release of the locking member and to compress said spring, whereupon said locking member is urged into locking position by the rear part of the accumulator under the action of said spring.

10. Automatic fire-arm according to claim 9, including means actuated by the pressure of the explosion gases in the barrel to shift the rear part of the accumulator forwardly to release the 1 locking member.

11. Automatic fire-arm according to claim 9, wherein the locking member is shaped to receive the rear` portion of the rear part of the accumulator beneath it when it has been shifted into locking position, whereby the locking member is locked in locking position.

12. Automatic lire-arm according to claim 9 wherein the locking member engages the breech block along inclined surfaces which cam the locking member into unlocking position upon release ing and releasing the breech block and comprising a locking member supported on the breech casing and normally disposed out of the path of the breech block, and a floating energy accumulator including a front part and a rear part movable relative to each other and both slidablein the casing, and a compression spring disposed between said parts, said parts lbeing movable by the breech block as it approaches its forward reversal position to release the locking member and move it into locking position.

16. Automatic lire-arm according to claim 1,

wherein the locking means comprises a pivotedk member swingable into and out of locking position, the energy accumulator including a portion underlapping the locking means in the operative position of the latter to hold the locking means in such operative position, and wherein thelsurfaces along which the locking means and breech block engage are inclined in such manner that the direction of the force transmitted by the breech block to the blocking means forms with the straight line connecting the center of the forcetransmitting area of said surfaces and the fulcrum of the locking means an angle which is greater than the angle of friction, so that upon removal of the said underlappping portion, un-

locking occurs automatically on rearward travelv of the breech block. Y

17. Automatic fire-arm according to claim 1,

wherein the energy accumulator includes a portion underlapping the locking means in the operative position of the latter to hold the locking means in such operative position, and wherein the faces along which the locking means and the breech block engage each other are inclined to the direction of rearward travel of the breech block to such a degree that upon removal of the underlapping portion of the energy accumulator from under the locking means, the latter is automatically cammed out of locking position by the rearwardly traveling breech block.

HANNS LIPPERT.

ERWIN HEPPERLE.

REFERENCES CITEDV The following references are of record in the file of this patent: Y

UNITED STATES PATENTS Number Name Date 624,145 Young May 2, 1899 FOREIGN PATENTS Number Country Date 336,395 Germany Apr. 30, 1921 489,752 Great Britain Aug. 3, 1938 706,158 Germany May 19, ,1941 

